Design of a High-Level Diagnostic System

Abstract

The use of vibration signals produced by the operation of a machine to control its operations and detect developing faults is appealing because of the ruggedness of vibration sensors and their ease of placement. A diagnostic system that employs a few sensors, remotely located from a number of vibration generating mechanisms, to analyze the performance of these mechanisms is termed a “high-level” diagnostic system. The goal of such a diagnostic system is to infer from the remote vibration sensors the characteristics of the internal sources (such as forces and pressures) which could not be easily measured directly. The use of multiple sensors and advanced signal processing methods is necessary for such a system to be viable. A series of studies on vibration excitation, propagation, sensing, and signal processing that demonstrate the basic feasibility of such a diagnostic system are described. The design of a high-level diagnostic system for detecting the combustion and gear mesh excitations in a diesel engine analysis is presented, along with the results of a preliminary application of the system.